Airless and high-volume, low-pressure (HVLP) air sprayers are really two different types of machines. Although they both spray paint, they do it in different ways, and neither machine is the best one for all types of painting jobs. If you are considering buying a paint sprayer, get to know the capabilities and limitations of both machines so you'll get the best results from the one you purchase.
The spray pattern from an HVLP sprayer is created by compressed air. It flows through an air hose into a paint cup from a compressor and mixes with the material in the cup. The mixture of paint and air emerges from the tip as a spray of atomized paint particles. You can adjust the quantity of paint in the paint pattern, as well as the shape of the pattern, by adjusting the air pressure. Tradespeople use HVLP sprayers primarily for furniture and automotive finishing. They work best with fast-drying, thin materials like lacquer, urethane and stains.
An airless spray gun is connected to a pneumatic pump that forces paint through its tip. The spray pattern isn't created by mixing paint with air, but by forcing the paint at high pressure through a tiny opening. The pattern contains more paint and covers more quickly. An airless sprayer can spray thick paints, adhesives and other bulky materials and is the best tool for house-painting and other large jobs that require a high volume of paint over a wide area. Airless sprayers also work with stains but are not recommended for use with lacquer or automotive urethane.
Volume, not accuracy, is the primary advantage of an airless sprayer. You'll end up creating drips and runs if you try to use it over a small area with thin material because the spray pattern is coarser and harder to control than an HVLP gun. On the other hand, you can cover a large area in a fraction of the time it would take to do it with an HVLP gun, and there is usually no need to thin the paint before you spray it. Remember that the spray from an airless sprayer is under high pressure and dangerous.
If you have to buy one sprayer for multi-purpose use around the house, consider a hand-held airless gun. Some models incorporate HVLP technology to make them suitable for spraying paint on walls, fences, outdoor furniture and even some indoor furniture. If you are considering a sprayer for shop use, though, make it an HVLP. It is more accurate and gives the best results with common shop-use painting materials, like lacquer and urethane. HVLP guns waste less material in overspray than airless ones and are easier to calibrate and clean.